Small, brown wrens in Northern Colorado focus of researchers who hope to learn their secrets

Scientists only starting to learn about the birds' songs and nesting habits

By Deborah Huth Price For the Reporter-Herald

Posted:
11/07/2012 09:28:27 PM MST

Nat Warning took this photo of a nesting canyon wren.
(Nat Warning)

Hikers, bicyclers, equestrians and climbers spend much time recreating in the canyons and foothills west of Loveland. Researchers are also there, exploring curiosities about wildlife sharing our space.

Imagine a guy at a bar who gets into a fight with another patron. His voice will probably sound different when he talks to the bartender than when he confronts his opponent. That's the analogy that assistant professor Lauryn Benedict uses to describe how the songs of canyon wrens change when they are faced with an intruder.

Benedict, who teaches in the school of biological sciences at the University of Northern Colorado in Greeley, has been researching the songs of canyon wrens throughout the Front Range.

Recreationists who spend time in the canyons west of Loveland have probably heard the cascading notes of the canyon wren. "They sing a very well-known, really beautiful clear ringing song that is the sound of the western canyon," says Benedict.

These small brown birds are year-round residents of the Front Range, and reside in cliff habitat. They are monogamous birds, explains Benedict, and very territorial. Their large territories are guarded usually by one male and one female.

Benedict and graduate student Nat Warning have spent a lot of time in natural areas and open spaces west of Loveland and Fort Collins, playing back recorded songs of male canyon wrens in the presence of their live counterparts. What they discovered is that individual canyon wrens will improve the quality of their song when they hear the song of a perceived intruder. In other words, Benedict explains, they add aggressive sounds to the end of their songs, and use lower frequencies similar to what a larger bird might use.

A rock wren perches on a rock.
(Nat Warning)

This is where the "bar fight" voice comes in.

While canyon wrens are known for nesting in pretty inaccessible places, usually crevices in canyon ridges, Benedict and Warning have studied a few nests this year in buildings near natural area parking lots. "We think of them as a pretty elusive species," says Benedict, "but sometimes they are right next to people."

Benedict and Warning have also begun banding canyon wrens this year to further study their territory ranges, mating behavior, and gender-specific traits. Small leg bands are placed on birds with specific identifying numbers that help the researchers track the birds in the future.

"If people have canyon wrens in their backyards," adds Benedict, "and would like research done on them, we'd like to know."

The songs of canyon wrens are not the only interest of the UNC researchers. Warning is particularly interested in the rock wren. The male of this species serenades listeners with a huge variety of songs with up to 100 syllable types. Their songs are made up of repeated syllables of four, "like a record that's stuck," says Benedict, "and then they move on to the next thing."

Both canyon and rock wrens live in ridges and dine on insects. Rock wrens breed along the Front Range, but spend winter in southern Colorado, New Mexico, and Texas, says Warning. In addition to their song differences, an easy way to identify the two is to look for the white neck patch on the canyon wren, or the curious habit the rock wren has of bobbing up and down when it sings, "like it's doing deep knee bends."

The most interesting aspect of the rock wren to Warning is the nests these little birds build deep inside rock crevices. Stone foundations, or patios, extend out from the nest. Most likely built by females, these patios or walkways include upwards of 300 stones (approximately 2 centimeters by 2 centimeters).

While there is much speculation as to what the patios are for, the true benefit has not been documented. Warning observed 20 different nests over the summer, making note of how deep the nests were, which way they were oriented, and looking for other patterns.

Do the patios help make the nest opening smaller? Do they fill in cracks so chicks don't fall out? Does the patio keep the nests warmer or drier? Is it used as a sexual display? Next year, Warning hopes to answer some of these questions by putting out cameras on some of the nests to further observe the birds' activity.

Warning wants to make people, especially climbers, aware that both species may be nesting nearby so that the birds are not disturbed. A hand hold might just be the patio of a nesting rock wren.

Each month in Outpost, Deborah Huth Price will write about the studies telling us more about the natural world around us. To find out more about canyon and rock wren studies done by UNC researchers, visit assistant professor Lauryn Benedict's web page: unco.edu/biology/lbenedict.

Rock wrens make a patio-like structure outside their nests with rocks.
(Nat Warning)